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Does SPI need termination resistors?
you do not need a series termination resistor on the SPI lines unless the length of the line is very long and the clock rate very high. A pull up resistor maybe needed on the MISO on things like SD cards as it will stop the line floating and can also be used as a way to detect if the SD card is inserted.
How do you terminate SPI?
Place series termination (something like 22 Ohms) at the source of the clock, and split the trace after that. Length-match the split trace to each slave. Voila!
How is data clocked on the SPI bus?
SPI is a serial bus and consists of a minimum of four signals. Data is clocked out in serial form from master to slave on the MOSI line, and data is clocked in in serial form from slave to master on the MISO line. One or more Chip Select (CS_L) signals is implemented to select a particular slave device in multi-slave configurations.
Which is the best description of the SPI bus?
The Serial Peripheral Interface (SPI) Bus is an electrical engineer’s best friend. In its simplest form, it is a point-to-point interface with master/slave relationship. The signals are all uni-directional and point-to-point, which allows for simple series termination for high-speed transmission line operation.
When to put a pullup on a SPI line?
You don’t need pullups or pulldowns on SPI lines. When used, SPI lines are always explicitly driven both directions. However, it can be good to put a pulldown (or pullup) on the MISO line. That is because this line is only driven by a slave when it’s slave select line is asserted.
What should the ground clip be for SPI bus termination?
Probing anywhere else will likely give you a distorted waveform and trick you into thinking that things are worse than they really are. Also, make sure that your ground clip is as short as possible. Conclusion: Switch to source termination with a 33 to 50 ohm resistor and you should be fine. The usual caveats apply.